Two students measure the speed of sound in air on a playing field.
Student A stands 400 m from student B. Student A bangs two cymbals together. Student B starts a stopwatch when they see the cymbals hit and stops it when they hear the sound.
The Table shows the results.
Table
| Attempt | Time in s\text{s}s |
|---|---|
| 1 | 1.22 |
| 2 | 1.15 |
| 3 | 1.30 |
| 4 | 1.17 |
Calculate the mean time.
Calculate the speed of sound in air from these results.
Explain why student B can start the stopwatch when they see the cymbals hit.
Describe one change to the method that would make the measurement of the speed of sound more accurate. Give a reason for your answer.